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Hormones and Libido: Foundational Evidence Review

Status: draft compiled 2026-04-28. Purpose: harsh fact-check of a draft blog post claim set on hormones-and-libido. Method: every paragraph is grounded in primary or near-primary sources, with confidence tags ranging from C1 (primary RCT or guideline) through C5 (folk model not located in indexed literature). Where the draft's framing diverges from the published evidence, that gap is named directly rather than smoothed over.

The first claim that has to be examined sceptically is the framing one. The draft proposes two libido "axes," a masculine T-driven type and a feminine E/P-driven type, each with its own internal phenomenology (always-on versus often-off, genital versus body-wide sensitivity, sharp versus gradual post-orgasm decline, longer versus shorter refractory). What the actual sexology literature contains is something related but importantly different. Rosemary Basson's 2000 paper in the Journal of Sex and Marital Therapy proposed a circular, intimacy-driven model of women's sexual response in which a "responsive" component of desire often follows arousal rather than preceding it, in explicit contrast with the linear Masters-and-Johnson sequence; the abstract states that the model is meant "to prevent diagnosing dysfunction when the response is simply different from the traditional human sex-response cycle and to more clearly define subgroups of dysfunction." This is not a hormone axis. Basson nowhere claims that responsive desire is driven by estrogen-progesterone and that spontaneous desire is driven by testosterone. Subsequent reviews by Chivers and Brotto have repeatedly stressed that responsive versus spontaneous desire is best understood as a continuum that crosses sexes rather than mapping onto a male/female or T/E binary. The "two axes" framing of the draft therefore reads as a lay synthesis of (a) Basson's responsive-desire concept, (b) population-level sex-difference data on spontaneous sexual cognitions (Baumeister et al. 2001), and (c) trans community phenomenological reports. It is a folk model, not an established sexology construct. Sources: Basson 2000, PMID 10693116, Baumeister, Catanese & Vohs 2001 Pers Soc Psychol Rev, Chivers & Brotto 2017 European Psychologist controversies review. Confidence: C2 for the claim that the two-axes framing is not an indexed sexology construct, C3 for the lineage I've sketched.

The phenomenological details inside that two-axes claim survive somewhat better than the framing as a whole. There is meta-analytic evidence that men, on average, report more frequent spontaneous sexual cognitions, more masturbation, more partnered desire, and more variable willingness to forgo sex than women, with effect sizes that are not subtle but also not categorical (Baumeister et al. 2001 in Personality and Social Psychology Review). There is older but still-cited physiology suggesting men typically have a longer ejaculatory refractory period than women, with prolactin implicated as a mediator (Krüger and colleagues' work on orgasm-induced prolactin secretion). Genital-versus-subjective arousal concordance is famously lower in women than in men (Chivers et al. 2010 meta-analysis: r ≈ 0.66 in men, 0.26 in women), which is roughly compatible with the "body-wide sensitivity" intuition but is really about a different construct, namely the dissociation between physiological lubrication/vasocongestion and reported desire. None of these distinct empirical observations actually requires the hormonal grouping the draft proposes. Sources: Baumeister et al. 2001, Krüger et al. orgasm-induced prolactin paper, Chivers et al. 2010, PMC2811244. Confidence: C2.

Once the framing is set aside, the next claim to test harshly is the assertion that "testosterone has the strongest effect on libido," especially in cis women. The simplest summary of the actual evidence base is that testosterone has the strongest effect on libido that pharmacology has been able to demonstrate as a therapy when sexual desire is the endpoint, but this is not the same as testosterone being the dominant endogenous driver of women's day-to-day desire, and the gap between those two statements is wider than the draft acknowledges. The 2019 Lancet Diabetes & Endocrinology systematic review and meta-analysis by Islam, Davis, Bell and colleagues pooled 46 reports of 36 RCTs with 8,480 participants, and found that testosterone produced a mean increase of 0.85 satisfactory sexual events per month (95% CI 0.52 to 1.18), a standardised mean difference of 0.36 (95% CI 0.22 to 0.50) for desire, 0.28 for arousal and 0.25 for orgasm. These effect sizes are statistically robust but clinically modest, roughly "one extra satisfying sexual event a month above placebo," and they are derived almost entirely from postmenopausal women, often on background estrogen. Sources: Islam, Davis et al. 2019, Lancet Diabetes Endocrinol, PMID 31353194, 2019 Global Consensus Position Statement, PMC6821450. Confidence: C1 for the meta-analytic effect sizes, C2 for the framing.

The Wåhlin-Jacobsen 2017 cross-sectional study in 428 premenopausal women, awarded the 2016 ISSM Female Sexual Dysfunction Prize, deserves to be cited every time someone says "T is the master libido hormone in women," because it is one of the largest and best-controlled endogenous-androgen studies and its results are pointedly mixed. The authors found that women with low sexual desire had significantly lower mean free testosterone and androstenedione than women without low sexual desire, but that "none of the androgens were associated with FSD in general or with HSDD in particular." In other words, total testosterone and DHEA-S were not associated with hypoactive sexual desire disorder, and the only significant correlation was a fairly soft one between free T or androstenedione and a low-desire subgroup, with psychosocial variables explaining as much variance as androgen levels. The honest reading of this study is that endogenous androgen levels in healthy premenopausal women are weak predictors of clinically meaningful low desire, which directly undercuts any sweeping claim that T is "the main libido hormone." Sources: Wåhlin-Jacobsen et al. 2017, J Sex Med, PMID 28117267. Confidence: C1.

The draft's testosterone-supremacy framing also has to confront the menopause longitudinal data. The Melbourne Women's Midlife Health Project, Lorraine Dennerstein's 8-year prospective cohort, examined waning ovarian estradiol and testosterone alongside annual sexual-function measures and concluded that the menopause-related decline in women's sexual desire and responsiveness was significantly correlated with falling estradiol but not with falling testosterone. Susan Davis and others have noted the same pattern in their reviews. Cappelletti and Wallen's 2016 review in Hormones and Behavior is even more pointed: "estrogen-only therapies that produce periovulatory levels of circulating estradiol increase sexual desire in postmenopausal women," whereas "testosterone at supraphysiological, but not at physiological, levels enhances the effectiveness of low-dose estrogen therapies," and "the likelihood that an androgen-only clinical treatment will meaningfully increase women's sexual desire is minimal." That review is an important counterweight to the trade-press habit of describing testosterone as the dominant female libido hormone, because it points out that clinical efficacy in the trial record is largely tied to supra-physiological androgen exposure rather than to restoring endogenous physiology. Sources: Dennerstein, Lehert & Burger 2005 hormones and sexuality discussion, PMID 16414328, Cappelletti & Wallen 2016, Horm Behav, PMID 26589379 and PMC4720522. Confidence: C1 for the Cappelletti/Wallen conclusions, C2 for the broader synthesis.

The Roney and Simmons 2013 daily-diary study of natural menstrual cycles is another inconvenient datum for the simple T-supremacy story. Roney and Simmons sampled saliva for estradiol, progesterone and testosterone across 1–2 cycles and matched daily reports of sexual desire and behaviour; they found that within-cycle desire variation was positively predicted by estradiol, negatively predicted by progesterone, and that "no significant effects of testosterone concentrations [were observed] when controlling for the effects of estradiol and progesterone." That is, when free testosterone and estradiol are simultaneously modelled at the daily level in healthy young cycling women, testosterone drops out and estradiol-with-progesterone do the explanatory work. This is, in mechanism terms, the opposite of the draft's framing for cis women. It does not prove that estradiol is the master hormone (animal models point to it more strongly than human ones do), but it does mean that the evidence base for "T is the dominant libido hormone in women" cannot rely on within-person, within-cycle physiology. Sources: Roney & Simmons 2013, Horm Behav, PMID 23601091. Confidence: C1.

What testosterone does have, and what justifies its place in clinical practice, is RCT evidence in postmenopausal women. The 2000 Shifren et al. NEJM trial of transdermal testosterone in surgically menopausal women on background estrogen demonstrated dose-dependent improvements in sexual desire, fantasy, and pleasure with a 300 µg/day patch achieving roughly mid-to-upper premenopausal serum free T levels. The follow-on Braunstein 2005 surgically-menopausal HSDD trial published in Archives of Internal Medicine reported that women on the 300 µg/day patch had a 67% versus 48% increase from baseline in sexual desire and 79% versus 43% increase in satisfying sexual activity, all on background estrogen. The 2008 Davis APHRODITE NEJM trial then tested the patch in postmenopausal women not taking estrogen and again found efficacy on sexual desire and satisfying sexual events, although the absolute increment over placebo remained modest (roughly one additional satisfying event per month). Sources: Shifren et al. 2000 NEJM article page, Braunstein et al. 2005 Arch Intern Med, PMID 16043675, Davis et al. 2008 APHRODITE NEJM article page. Confidence: C1 for trial outcomes, C2 for the effect-size summary.

Despite that record, the FDA repeatedly refused to approve a testosterone product for cis women. Procter & Gamble's Intrinsa patch was rejected by an FDA advisory committee in December 2004 on the grounds of inadequate long-term cardiovascular and breast-cancer safety data, and Procter & Gamble withdrew the application; Intrinsa later received European approval but never re-cleared US review. BioSante's LibiGel testosterone gel failed its Phase III BLOOM trials around 2011 to 2012 because, although both arms improved, the placebo response was so high that the active drug did not separate from placebo on the FDA-required co-primary endpoints. The cautionary read of this regulatory history is that the published meta-analytic effect sizes are real but small enough that ordinary placebo arms can erase them, and that no T product is FDA-approved for women in 2026; Australia's AndroFeme cream and several compounded-T workarounds are the practical clinical vehicle outside North America. The recent ISSWSH and Global Consensus statements explicitly recommend off-label one-tenth-of-male-dose use to keep total T within the premenopausal physiological range. Sources: Healio 2012 FDA panel rejection of testosterone patch coverage, California Healthline on P&G withdrawing Intrinsa, 2019 Global Consensus Position Statement, PMC6821450, ISSWSH 2021 Clinical Practice Guideline, PMC8064950. Confidence: C2.

The "upper-female-range without masculinization" claim deserves a careful look because it is partly true and partly incautious. The 2019 Global Consensus Position Statement (Davis, Baber, Panay, Bitzer and ten endorsing societies) insists that physiological dosing means "doses that approximate physiological testosterone concentrations for premenopausal women" and recommends repeat-testing 3–6 weeks after initiation and every 6 months thereafter. The 2021 ISSWSH Clinical Practice Guideline operationalises that as roughly one tube/packet over ten days of 1% T gel (i.e. one-tenth of the male dose, ~4 drops/day), or 5–10 mg/day of the AndroFeme 1% cream, with the explicit instruction that "total testosterone does not significantly exceed the upper limit of the reference range for normal premenopausal women." Crucially, the consensus also states that "there is no blood level that is a treatment goal for testosterone therapy, as serum concentrations do not predict treatment efficacy," but at the same time "if the level is supraphysiologic, even in the absence of androgenic adverse events, the dose should be reduced." Side effects in trials at physiological dosing are usually mild acne and modest hair growth, with overt masculinization (voice change, clitoromegaly, alopecia) considered uncommon below upper-premenopausal serum totals. So "upper-female-range T without masculinization" is consistent with current guidelines, but only if dose titration and monitoring are done carefully and the physiological target is respected; in real-world compounded-T practice, supraphysiological levels are common and are precisely where masculinization risk is concentrated. The claim is therefore TRUE in principle and frequently violated in practice. Sources: Davis et al. 2019 Global Consensus Position Statement, PMC6821450, Parish, Simon, Davis et al. ISSWSH 2021 CPG, PMC8064950. Confidence: C1.

The estrogen-versus-testosterone comparative-strength question is where the draft's "secondary E/P axis" framing collides hardest with the literature. The Women's Health Initiative did not show that systemic estrogen-only or estrogen-plus-progestin meaningfully increased libido as a sexual-function outcome, and a recent 2023 systematic review and meta-analysis update of hormone therapy for sexual function in peri- and postmenopausal women concluded that estrogen therapy, estrogen-plus-progestogen therapy, tibolone, and SERMs produce "no effect to small benefit on sexual function" relative to control, although vaginal estrogen reliably improves dyspareunia and lubrication. That looks like superficial support for "estrogen is weaker for libido than testosterone." But the deeper-cut data also includes the Cappelletti-Wallen synthesis above (estradiol at periovulatory levels does increase desire), the Dennerstein cohort (estradiol, not testosterone, tracks the menopausal desire decline), and Roney-Simmons (within-cycle desire is estradiol-positive, progesterone-negative). The fairer reading is that exogenous systemic estrogen alone, at typical hormone-replacement-therapy doses, does not reliably restore libido in a large fraction of postmenopausal women, but endogenous estradiol fluctuations strongly track desire in cycling women and supraphysiological-T-on-top-of-E is more effective than either alone in the menopause. "Estrogen is weaker than testosterone for libido" is therefore an oversimplification that is true for some clinical endpoints in postmenopausal women on HT but false at the within-cycle physiology level in healthy cis women. Sources: Hormone therapy for sexual function in peri- and postmenopausal women systematic review 2023, PMC10227948, Cappelletti & Wallen 2016, PMC4720522, Roney & Simmons 2013, PMID 23601091. Confidence: C1 for the underlying datasets, C2 for the synthesis.

The SHBG mechanism makes the "more estrogen for libido" intuition still more dangerous in practice. Oral ethinyl estradiol (and to a lesser extent oral 17β-estradiol) is a potent inducer of hepatic sex-hormone-binding globulin, and a 2014 systematic review and meta-analysis by Zimmerman and colleagues showed combined oral contraceptive users have a 40-60% reduction in free testosterone and substantial declines in the free androgen index. Panzer et al. in 2006 documented that SHBG remains elevated for at least six months after OCP discontinuation in women presenting with sexual dysfunction. The clinical consequence is that prescribing oral estrogen as a "libido boost" can actually drop bioavailable T enough to worsen sexual function in some women, and that part of the perceived libido benefit of switching from oral COCPs to transdermal estradiol is probably a SHBG correction rather than estrogen action per se. This is a major reason why ISSWSH, the Endocrine Society and the European Society of Sexual Medicine all flag oral combined contraceptives and oral estrogen as confounders for any clinical hypothesis about estrogen and desire. Sources: Zimmerman et al. 2014 Hum Reprod Update, PMC3845679, Panzer et al. 2006 J Sex Med, PMID 16409223. Confidence: C1.

Progesterone is the most over-claimed and under-evidenced node in the draft, and it deserves the harshest treatment. Folk-trans and bioidentical-HRT cultures both promote oral micronized progesterone as a libido enhancer; the published trial record does not support that. Saadat et al. 2002 in Fertility and Sterility randomised estrogen-treated postmenopausal women to 200 mg/day oral micronized progesterone versus 10 mg/day oral medroxyprogesterone acetate and found neither agent had any influence on mood or libido. Wren et al. 2003 found 32 mg/day transdermal progesterone cream had no effect on sexual desire in postmenopausal women. Roney and Simmons 2013 found endogenous progesterone was negatively associated with daily desire in cycling women, statistically mediating the luteal-phase fall in desire. The 2023 Saraf et al. study of progesterone in feminizing GAHT (Journal of the American Pharmacists Association) reported no difference in patient satisfaction with libido between progesterone-using and progesterone-naïve transfeminine cohorts, although it did find better breast-development satisfaction and modest mental-health gains. Pharmacologically, the GABA-A positive-allosteric-modulator metabolite allopregnanolone is sedating, and high-dose progestins (cyproterone acetate, MPA) are explicitly used clinically to suppress sexual desire in men with paraphilic disorders. The honest summary is that progesterone, as a class effect, is at best neutral and at worst suppressive for libido in the published literature; "oral natural progesterone raises libido in some when low on E" is an N-of-many anecdotal claim with no controlled trial behind it. Sources: Saadat et al. 2002 Fertil Steril, micronized progesterone vs MPA on mood/libido, Roney & Simmons 2013, PMID 23601091, Saraf et al. 2023 J Am Pharm Assoc on progesterone in feminizing HRT, PMID 37549733, Aufrere & Sirota 2023 transfemscience progestogens and sexual desire literature review, Söderpalm et al. 2003 progesterone sedation, PMID 14644065. Confidence: C1 for the trial record, C2 for the synthesis. The "progesterone-raises-libido in some" anecdotal pattern is C4.

DHEA, often suggested as a dark-horse libido hormone, also fails to clear the harsh-fact-check bar in cis women with normal adrenal function. Elraiyah et al.'s 2014 J Clin Endocrinol Metab clinical-review meta-analysis of 23 RCTs concluded that systemic DHEA in postmenopausal women with normal adrenal function did not significantly improve libido or sexual function and was associated with mild androgenic side effects. The Cochrane review reported similar uncertainty: a possible small improvement in sexual function, but uncertainty about quality-of-life and a clear signal of androgenic side effects. Labrie's intracrinology framework and the FDA-approved intravaginal DHEA (prasterone, Intrarosa) reframed DHEA as a local genital-tract therapy for vulvovaginal atrophy and dyspareunia rather than a systemic libido drug, with intravaginal 6.5 mg/day DHEA improving dyspareunia and vaginal-atrophy symptoms but with the systemic-libido story essentially abandoned. So claims that DHEA supplementation broadly increases libido in healthy postmenopausal women are not supported by the meta-analytic record. Sources: Elraiyah et al. 2014 J Clin Endocrinol Metab DHEA systematic review, PMC5393492, Labrie intracrinology and menopause review, PMID 30130283. Confidence: C1.

Prolactin deserves more attention than the draft gives it. Hyperprolactinemia (whether from prolactinoma, dopamine antagonists, hypothyroidism, or stress) is consistently associated with hypoactive sexual desire disorder in both men and women; an Italian J Sex Med 2024 cross-sectional study showed women with elevated monomeric prolactin had markedly lower scores across desire, arousal, lubrication, orgasm and satisfaction, and that the deficit was largely independent of estradiol and testosterone, suggesting central dopaminergic mechanisms. Krüger and colleagues' work showed that orgasm produces a sharp acute rise in prolactin in both sexes, and post-orgasm prolactin is implicated as one of the candidate neurochemical correlates of the post-ejaculatory refractory period. There is also a small literature suggesting that very low prolactin in women correlates with a more disinhibited libido profile; this is interesting but the evidence is preliminary. The clinical takeaway, which the draft should incorporate, is that any patient (cis or trans) with sustained low libido on otherwise reasonable hormone numbers deserves a prolactin check before further hormonal tinkering. Sources: Krüger et al. orgasm-induced prolactin secretion review, Italian J Endocrinol Invest hyperprolactinemia and sexual function 2024 article, Low-prolactin HSDD women profile paper, Springer 2023. Confidence: C2.

The transfeminine longitudinal data on libido is more interesting and more nuanced than either trans-community wisdom or the draft acknowledges. The European Network for the Investigation of Gender Incongruence (ENIGI) is the largest prospective cohort: Defreyne and colleagues followed 401 trans women and 364 trans men across 36 months of hormone therapy and reported that, in trans women, total, dyadic and solitary Sexual Desire Inventory scores all decreased during the first three months of feminizing HT (estradiol plus antiandrogen), but at 36 months total and dyadic SDI scores were higher than baseline, while solitary scores had returned to baseline. Crucially, they found "no correlation between sexual desire and absolute serum testosterone levels," suggesting that the recovery and reorganisation of desire is driven by relational, dysphoria-related and surgical factors rather than directly by androgen titres. This is broadly compatible with the draft's claim that "some transfem people regain feminine-style libido after long-term feminine hormone levels — others do not," in the sense that the cohort is heterogenous. But the draft's hormonal framing of the "feminine-style" descriptor is not really validated by ENIGI, which doesn't measure phenomenological style so much as quantity of desire. Sources: Defreyne et al. ENIGI sexual desire results, JES 2020 abstract, Defreyne et al. 2020 J Sex Med ENIGI sexual desire paper. Confidence: C2.

Vaginoplasty-prep and post-vaginoplasty orgasm data add another layer. NYU's robotic peritoneal-flap vaginoplasty cohort reported orgasmic ability in 86% of patients within one year, and the broader literature converges on roughly 80–90% post-vaginoplasty orgasmic capacity at 6–12 months, with continued late conversion to orgasmic capacity in some patients beyond a year. Reports of multi-orgasmic patterns and shortened refractory periods after vaginoplasty exist in the trans surgical literature but are largely descriptive, and the data are not strong enough to support a confident claim that orgasm phenomenology is reorganised by long-term feminine hormones in a uniform way. The cleanest empirical statement is that many transfem people on long-term feminizing HRT report a more dispersed, partner-context-driven, less acutely peak-and-crash desire profile, and many do not; what is not established is that this is a hormone-level rather than an embodiment, dysphoria-resolution, or anatomy-after-surgery effect. Sources: Salgado et al. NYU robotic peritoneal-flap vaginoplasty orgasm follow-up, PMID 35337785, Sexual satisfaction after gender-affirming surgery review, PMC9417774. Confidence: C3.

The post-orgasm hormonal-decline picture is also more boring than the draft's "sharp" versus "gradual" framing implies. In men, total testosterone shows little or no acute change in the first hour after a single orgasm in most modern studies; the more robust finding is that prolactin rises sharply post-orgasm in both sexes, sustains for roughly 60 minutes, and tracks subjectively with sexual satiety. Dopamine, oxytocin and endogenous opioid changes appear to do most of the work for the immediate refractory period, not testosterone. So the draft's "sharp post-orgasm T drop in masculine type" is essentially wrong as stated; what's sharp post-orgasm is prolactin elevation and dopamine drop, and what is true cross-sex is that the ejaculatory refractory period in men is longer on average than the equivalent in women, but with substantial individual variation and unclear hormonal mediation. Sources: Krüger et al. orgasm-induced prolactin secretion review, Levin 2009 J Sex Med refractory time review of male and female literature. Confidence: C2 for the prolactin part, C3 for the negative claim about acute T decline.

What about the cyclical menstrual-cycle libido peak? There is a real, replicable peri-ovulatory desire bump in many studies, and an upstream peri-ovulatory testosterone peak coincides with it; that coincidence is the source of the "T drives ovulation-time libido" folk model. The Roney and Simmons 2013 daily-saliva study, however, explicitly disentangled the three steroids and found estradiol, not testosterone, was the within-cycle driver, with progesterone responsible for the luteal decline. A 2022 multi-method study (Jones et al., J Sex Res) and several follow-up Roney studies broadly converge on the same answer: estradiol is the primary within-cycle modulator of subjective desire, progesterone suppresses, and testosterone is a weaker independent contributor at physiological cycle ranges. This is one of the cleanest places where the draft's T-supremacy framing for cis women is factually wrong. Sources: Roney & Simmons 2013, PMID 23601091, Jones et al. 2022 J Sex Res multi-method cycle desire paper. Confidence: C1.

To round out the picture, a brief note on flibanserin and bremelanotide. The 2015 FDA approval of flibanserin (Addyi) for premenopausal HSDD generated about half of one extra satisfying sexual event per month over placebo; the FDA advisory committee voted 18 to 6 in favour but with explicit concern about the marginal effect size. Bremelanotide (Vyleesi), approved 2019, also produces small-to-moderate improvements with significant nausea limitations. These are mentioned because the draft's hormonal framing implicitly treats hormone manipulation as the principal lever for desire, but the broader literature shows that even pharmacologically active CNS agents on the desire-distress axis have effect sizes that are real but small, and that low-desire trajectories in healthy cycling women are driven heavily by relational, contextual and stress-axis factors rather than by any single steroid. Sources: Joffe et al. 2016 NEJM Perspectives on flibanserin approval, Flibanserin 2015 FDA approval label. Confidence: C2.

A final note on the draft's overall framing that "T is the main libido hormone, E and P secondary." For postmenopausal cis women on background estrogen, there is a defensible RCT-grounded case that supplementary T at upper-physiological levels improves desire and satisfying sexual events, and that that effect is more reliably demonstrable than estrogen-alone systemic HT effects on libido. For premenopausal cis women, the within-cycle, cross-sectional and HSDD-association evidence does not support T-supremacy and points strongly to estradiol-with-progesterone-suppression as the within-cycle physiology, with endogenous T levels weakly associated at best with low-desire status. For trans women, the longitudinal ENIGI data show desire decreases in the first months of androgen suppression, then re-equilibrates by 36 months without correlating with serum T levels. Calling T "the main libido hormone" is therefore an over-generalisation that imports postmenopausal-clinical-trial findings into populations and physiologies where the evidence does not carry it. The more accurate one-line summary is that hormones modulate libido on multiple axes, that estradiol and testosterone both matter and interact, that progesterone is mostly neutral-to-suppressive, that prolactin elevation suppresses, and that even the strongest single-hormone manipulations produce clinically modest mean improvements that are easily masked by relational context, body-image, prior trauma and partner factors. Confidence: C2.

Verdict on draft claims

Claim 1: Two axes of libido — masculine T-driven (always somewhat on, genital-localized, sharp post-orgasm drop, long refractory) vs feminine E/P-driven (often off, slower ignition, body-wide, short refractory, gradual post-orgasm decline). KIND-OF-TRUE in its phenomenological description (the population-level male/female differences in spontaneous desire frequency, refractory length and arousal concordance are real), FALSE as a hormone axis (no indexed sexology source describes "feminine libido" as an E/P-driven axis or "masculine libido" as a T-driven axis; this is a folk synthesis of Basson's responsive desire model and lay sex-difference literature). The "sharp post-orgasm T drop" specifically is not supported by the post-orgasm hormone literature. Source: Basson 2000, Baumeister et al. 2001, Krüger et al..

Claim 2: Testosterone has the strongest effect on libido. KIND-OF-TRUE for postmenopausal cis women on estrogen background as a pharmacological intervention with the most consistent RCT evidence (Islam-Davis 2019 meta-analysis, +0.85 satisfying events/month), but FALSE as a statement about endogenous physiology in premenopausal cis women, where Wåhlin-Jacobsen and Roney-Simmons show endogenous T is a weak or null predictor of within-cycle desire. Source: Islam et al. 2019, Wåhlin-Jacobsen et al. 2017, Roney & Simmons 2013.

Claim 3: Some women supplement T to upper-female range for higher libido without masculinization. TRUE, with caveats. Both the 2019 Global Consensus and the 2021 ISSWSH guideline endorse off-label physiological-range T (typically one-tenth of male dose, e.g., 5–10 mg/day AndroFeme cream), with the explicit goal of staying within the upper premenopausal range and a low rate of masculinizing side effects in trials. Real-world compounded-T practice frequently exceeds these levels, where masculinization risk concentrates. Source: Davis et al. 2019 Global Consensus, ISSWSH 2021 CPG.

Claim 4: Estrogen has a weaker effect on libido than T. KIND-OF-TRUE for postmenopausal-HT clinical endpoints (the 2023 systematic review found estrogen alone produced no-to-small benefit on sexual function), FALSE for within-cycle physiology in cycling women (Roney-Simmons; Cappelletti-Wallen), and complicated by the SHBG-mediated free-T suppression caused by oral estrogen. The blunt framing oversimplifies. Source: 2023 hormone therapy and sexual function meta-analysis, Cappelletti & Wallen 2016, Roney & Simmons 2013, Zimmerman et al. 2014 SHBG meta-analysis.

Claim 5: Some transfem people regain feminine-style libido after long-term feminine hormones — others do not. KIND-OF-TRUE in the quantity-of-desire dimension (ENIGI shows total/dyadic SDI rises above baseline by 36 months in most but not all, with no T-level correlation), but the "feminine-style" qualifier is not validated by the hormonal-cohort data; the longitudinal recovery seems driven by gonadectomy, dysphoria reduction and relational factors as much as by long-term hormone levels. Source: Defreyne et al. ENIGI 2020.

Claim 6: Progesterone (oral natural) raises libido in some when low on E. NOT EVALUABLE / leaning FALSE as a general claim. Saadat 2002, Wren 2003, Roney & Simmons 2013, the Saraf 2023 transfem cohort, and the broader Cappelletti-Wallen synthesis all point to neutral-or-suppressive progesterone effects; no controlled trial supports a libido benefit. The "raises libido in some when low on E" formulation is anecdotal and could plausibly reflect allopregnanolone-mediated anxiolytic effects or mood improvement rather than primary desire effect. Source: Saadat et al. 2002, Roney & Simmons 2013, Saraf et al. 2023, Aufrere & Sirota transfemscience review.

Claim 7 (overall framing): T is "the main libido hormone," E and P secondary. KIND-OF-TRUE in postmenopausal pharmacology (T has the most robust RCT signal there), FALSE in cycling-women physiology (estradiol leads, progesterone suppresses, T weakly contributes), and OVERSIMPLIFIED globally because hormones, prolactin, dopamine, relational/cognitive factors and SHBG all interact and any single-hormone explanation is reductive. Source: synthesis of Cappelletti & Wallen 2016, Roney & Simmons 2013, Wåhlin-Jacobsen et al. 2017, Islam et al. 2019, 2019 Global Consensus.

C5 / unsourced claims encountered while writing

Compiled from research/libido/. Sources inline. This content was AI-generated and primarily AI fact-checked, not personally verified by the author.
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